At the Walker Stalker Con in Atlanta this weekend Greg Nicotero explains the on going clock easter eggs.
“He’s using Hershel’s watch with the chain,” explained Nicotero. “And then when he leaves, Maggie gets it, so of course if you see Maggie has the chain with the watch. And of course the time is 5:01 on the watch, because that was episode 501.
Nicotero continued, “So if you look at any of the stuff in the show…even when Carol picks up Rick’s watch off the table, it says 5:01. Every episode that we shoot we adjust the time on the watches and the clocks to whatever episode it is we’re shooting.”